Protection of high-tension direct-current motors in series.



T. VON ZWEIGBERGK. PROTECTION OF HIGH TENSION DIRECT CURRENT MOTORS INSERIES. APPLIOATION FILED MAR. 28, 1910.

1,006,619, Patented 0013.24, 1911.

WITNESSES. JNYENTDR THDBSTEN 'Sl'azsr 'ZWEIEBEHEK w] /%A- Hrs AT TDHJVEYCOLUMBIA PLANOGRAPH C0..WASH1NuToN, 04 c.

. UNITED STATES PATENT OFFICE.

THORSTEN VON ZWEIGBERGK, OF SOUTHPORT, ENGLAND, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

PROTECTION OF HIGH-TENSION DIRECT-CURRENT MOTORS IN SERIES.

Specification of Letters Patent.

Patented Oct. 24, 1911.

Application filed March 28, 1910. Serial No. 551,955.

To all whom it may concern:

Be it known that I, THORSTEN VON ZWEIG- BERGK, a citizen of the UnitedStates, residing at Southport, England,have invented certain new anduseful Improvements in or Relating to the Protection of High-TensionDirect-Current Motors in Series, of which the following is aspecification.

This invention relates to improvements in the automatic protection ofhigh-tension direct-current motors when operated in permanent series.Suppose a number, say 4, high-tension direct-current motors areconnected in series with an automatic circuit breaker: If one of thelast motors fails, a flash will take place between the brushes or overthe commutator of the motor, but the circuit breaker may not act becausethe motors in front of the damaged motor will give enough counterelectromotive force to prevent the current from rising above the limitfor which the circuit breaker is set. The result is that the areestablished at the damaged motor may continue indefinitely andcompletely burn out the motor.

The object of this invention is to obviate this danger.

This invention comprises the combination with a number of high-tensiondirect-current motors connected in permanent series with the currentsupply through a circuit breaker, of a supplementary circuit from themotor side of the circuit breaker connected in parallel with the seriesof motors when a flash takes place between the brushes and over thecommutator of a motor, for the purpose of insuring the action of thecircuit breaker. Preferably the supplementary circuit leads from themotor side of the circuit breaker to a terminal above the commutator ofeach motor whereby when a flash takes place between the brushes and overthe commutator of a motor, this flash will leap to the terminal andautomatically connect the supplementary circuit in parallel with theseries of motors and thus insure the action of the circuit breaker. Inorder to prevent a dead short from the circuit breaker through thedamaged motor, it is preferred to insert in the supplementary circuit aresistance sufficiently low to insure the action of the circuit breaker.

The accompanying drawing is a diagram showing one method of carryingthis invention into effect.

A number (in this case 4) high-tension direct-current motors representedby their commut-ators 1, 2, 3, 4, are connected in series and receivecurrent supply say from a trolley 5 through an automatic circuit breaker6.

If the field coils or armature coils of the last motor for example beaccidentally earthed, the commutation is at once affected and a flashwill occur from brush to brush of the commutator 4. As explained abovethis might take place without causing the circuit breaker to act and apermanent arc might be set up which would burn the motor 4. To preventthis I place immediately above the commutator of each motor an insulatedterminal 7, 8, 9, 10. These are all connected through resistance 11 tothe motor side of the circuit breaker. If now a flash takes place overthe commutator 4, this flash will at once leap to the terminal 10 whichis connected directly to the trolley through the resistance 11 and thecircuit breaker 6. The resistance is set low enough to insure that whensuch a flash takes place the circuit breaker will be operated withcertainty.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is,

1. The combination with a plurality of electric motors connected inseries, of a circuit breaker in series with said motors, and meanswhereby when any one of said motors flashes over said circuit breaker isconnected directly with the said motor.

2. The combination with a plurality of electric motors connected inseries, of a circuit breaker in series with said motors, an insulatedterminal adjacent to the commutator of each motor, and means forconnecting said terminal with the motor side of the circuit breaker.

3. The combination with a plurality of electric motors connected inseries, of a circuit breaker in series with said motors, a supplementarycircuit from the motor side of said circuit breaker, and means wherebyany motor which flashes over is connected with said circuit.

4. The combination with a plurality of electric motors connected inseries, of a circuit breaker in series with said motors, a supplementarycircuit from the motor side of said circuit breaker, and a plurality ofterminals connected with said circuit and located adjacent to thecommutators of their respective motors.

5. The combination with a plurality of electric motors connected inseries, of a circuit breaker in series with said motors, a supplementarycircuit from the motor side of said circuit breaker, means whereby thecommutator of any motor which flashes over is connected with saidcircuit, and a resistance in said circuit between the motors and thecircuit breaker.

6. The combination with a plurality of electric motors connected inseries, of a circuit breaker in series with said motors, a

supplementary circuit from the motor side of said circuit breaker, and aplurality of terminals connected with said circuit and located adjacentto the commutators of their respective motors, and a resistance in saidcircuit between the motors and the circuit breaker.

In Witness whereof, I have hereunto set my hand this eighteenth day ofMarch, 1910.

THORSTEN VON ZWEIGBERGK.

WVitnesses H. VVA'rsoN, H. lVILLIAMs.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

- Washington, D. 0.

